Does anyone know what this might be?

Every month around Ovulation time, I experience the worst pain I’ve ever felt in my life. It feels like a really sharp pain that starts in my butt and spreads to my pelvis and I’m completely unable to move for hours. This month I couldn’t move for 9 hours straight. I couldn’t get up to pee or anything. I went to the doctor a while ago and my Pap smear came back normal but this absolutely can’t be normal. It almost feels like something is rupturing when it happens. I’m 21 and this just started happening last year. Does this happen to anyone else? What could it be?